Liquid fuel pumping apparatus



Nbv. 4, 1969 K. A. w. KEMP ET AL LIQUID FUEL PUMPING APPARATUS Filed April 11, 1968 NVE N ATTORNEYS United States Patent 3,476,050 LIQUID FUEL PUMPING APPARATUS Kenneth Albert Walters Kemp, Ealing, London, and

Terence Redvers Wheeler, Highgate, London, England, assignors to C.A.V. Limited, London, England, a British company Filed Apr. 11, 1968, Ser. No. 720,521 Claims priority, application Great Britain, Apr. 17, 1967, 17,483/ 67 Int. Cl. F04b 13/02, 49/08; F04d 15/00 U.S. Cl. 1032 4 Claims ABSTRACT OF THE DISCLOSURE A liquid fuel pumping apparatus for supplying fuel to an internal combustion engine and including a pumping plunger which is moved inwardly in timed relationship with an engine, a pair of shuttle pistons, positioned within the fuel column extending from the pumping plunger to a delivery passage, a stop for limiting movement of the second shuttle piston during inward movement of the plunger and a spill passage uncovered by the second shuttle piston after a predetermined movement towards the stop whereby upon opening of the spill passage the first shuttle piston moves into contact with the second shuttle piston to urge it against the stop.

This invention relates to liquid fuel pumping apparatus for supplying fuel to internal combustion engines and has for its object to provide such an apparatus in a simple and convenient form.

A liquid fuel pumping apparatus in accordance with the invention comprises in combination, a pumping plunger, means for imparting inward movement to the pumping plunger in timed relationship with an engine with which the apparatus is associated, a bore to one end of which fuel is supplied under pressure by the pumping plunger during the inward movement thereof, first and second shuttle pistons slidable within said bore, a stop located at the other end of the bore and against which the second shuttle piston is driven during operation of the apparatus, a delivery passage extending from the other end of the bore and through which fuel flows to the engine, means for feeding proportioned quantities of fuel to said other end of the bore and to the portion of the bore lying intermediate the pair of shuttle pistons thereby to effect relative separation of the shuttle pistons and movement thereof away from the other end of the bore until the first shuttle piston is halted, the movement of the shuttle pistons causing outward movement of the pumping plunger, means whereby an additional quantity of fuel may be introduced to said one end of the bore to effect further outward movement of the plunger and valve means operable to permit the escape of any excess fuel from said one end of the bore when the movement of the first shuttle piston is halted.

In one example of a liquid fuel pumping apparatus in accordance with the invention and as illustrated in sectional side elevation in the accompanying drawing there is provided a body part in which is mounted a rotary cylindrical distributor member 11 which is arranged to be driven in timed relationship with an engine with which the apparatus is associated. At one end of the distributor member is formed a transversely extending drilling 12 in which is mounted a pair of pumping plungers 13. Moreover, surrounding the distributor member at this point is an annular cam ring 14 on the internal periphery of which are formed a plurality of pairs of inwardly extending and diametrically disposed cam lobes which through the intermediary of rollers 15 effect inward movement of the plungers 13.

3,476,050 Patented Nov. 4, 1969 Formed within the distributor member is a longitudinally extending bore 15 one end of which communicates with the drilling 12 and the other end of which is closed by a plug 16 which defines a stop for a purpose to be described. Furthermore, the end portions of the bore 15 together with an intermediate portion thereof are of enlarged diameter.

Extending from the end portion of the bore adjacent the, stop is a radially disposed delivery passage 17 which is arranged to register in turn and as the distributor member rotates, with a plurality of delivery ports 18 which are formed in the body part. The delivery ports in use, are connected respectively to the injection nozzles of the associated engine. Moreover, slidable within the bore are first and second shuttle pistons 19, 20 the shuttle piston 20 being located in the portion of the bore adjacent the aforesaid stop.

Mounted within the body part is a feed pump 21 the rotary part of which is driven from the end of the distributor member remote from the drilling. The feed pump is provided with an inlet 23 which in use, is connected to a source of liquid fuel and the outlet of the feed pump communicates with a fuel supply passage 22 formed in the body part. The capacity of the feed pump is such that an excess of fuel is always delivered and the excess quantity of fuel is allowed to spill back to the inlet of the feed pump by way of a spring loaded relief valve 24. In this manner the output pressure of the feed pump varies in accordance with the speed at which the apparatus and consequently the associated engine, is driven.

In communication with the intermediate portion of the bore 15 and the end portion of the bore which is adjacent the stop 16 are a pair of outwardly extending inlet passages 25, 26 respectively. These passages are arranged to register in turn and as the distributor rotates with two series of inlet ports 27, 28 respectively formed in the body part, The two series of inlet ports 27, 28 are connected respectively to a pair of ports 29, 30 which are formed in the wall of a cylinder 31 also formed in the body part. Mounted within the cylinder is an angularly adjustable throttle member 32 having formed in its periphery a pair of longitudinally extending grooves 29a, 30a. The inner end of the cylinder 31 communicates with the fuel supply passage 22 and the grooves extend to the end of the throttle member at this end of the cylinder. The ports 29, 30 and grooves 29a, 30a are so positioned that as the throttle member 31 is moved angularly the effective area of one of the ports increases whilst the eifective area of the other port decreases.

Extending from a point in the bore 15 which lies intermediate said intermediate portion of the bore and the end portion thereof which is adjacent the stop, is an outwardly extending spill passage 33 which is arranged to register in turn as the distributor rotates, with a plurality of spill ports 34 formed in the body part and which communicates either with the inlet of the feed pump or as shown, with a drain. The spill passages 33 is arranged to be covered by the shuttle piston 20 until the latter is a predetermined distance from the stop 16 as will be described.

The shuttle piston 19 is hollow in form and mounted therein is a spring loaded release valve 35 which is normally maintained by its spring in a closed position but which can be opened as will be described, to permit the flow of fuel from the end portion of the bore 15 which is adjacent the drilling 12, to the intermediate portion of the bore. Extending from the end of the bore which is adjacent the drilling 12, is a plurality of outwardly extending filling ports 36 which are arranged to register in turn and as the distributor rotates, with a filling passage 37 formed in the body part. The filling passage is in communication with a port 38 formed in the wall of a further cylinder in which is mounted a spring-loaded control valve 39. The inner end of the further cylinder is in communication with the fuel supply passage 22 by way of an annular passage so that the position of the control valve depends upon the speed at which the apparatus is driven. Moreover, formed in the periphery of the control valve is a tapered groove 40 which is in communication by way of drillings formed in the valve, with the inner end of the further cylinder. It is arranged, that at low speeds the port 38 is completely closed by the control valve but as the speed of operation of the apparatus increases, the port 33 is progressively opened to the groove 40.

The operation of the apparatus will now be described starting from the point at which the delivery passage 17 is just moving out of register with a delivery port 18 it being appreciated that the number of delivery ports is equal to the number of inlet ports in each series of inlet ports 27, 28, the number of spill ports 34, and the number of filling ports 36. As the distributor member rotates the inlet passages, 25, 26 move into register with one of each series of inlet ports and fuel flows through the aforesaid ports and passages into the end portion of the bore adjacent the stop and also to the intermediate portion of the bore. It should also be noted that at this time the pumping plungers 13 are permitted to move outwardly within the drilling 12. The flow of fuel through the inlet passages causes separation of the first and second shuttle pistons 19, 20 and also movement of the pistons in a direction away from the stop 16. Eventually the shuttle piston 19 contacts a step 41 defined at said one end of the bore and its movement is halted and consequently the movement of the shuttle piston 20 is also halted. The setting of the throttle member determines the proportion of the quantities of fuel fed in effect to opposite sides of the shuttle piston 20, and consequently it determines the quantity of fuel which will be supplied to the engine during the next pumping stroke of the apparatus. It should be emphasized that the total quantity of fuel which is supplied to the bore 15 through the inlet ports and passages is the same whatever the setting of the throttle member 32. Furthermore one of the filling ports 36 moves into register with the filling passage 37 and if the port 38 is exposed to the groove 40, a further quantity of fuel will be admitted to said one end of the bore and to the drilling 12. The plungers will therefore be moved outwardly an amount additional to that which they move out due to the movement of the shuttle pistons away from the stop.

Further rotation of the distributor member moves the inlet ports 25, 26 out of register with the inlet passages, 27, 28 and the filling port 36 out of register with the filling passage 37 and the relivery passage 17 moves into register with the next delivery port 18. Moreover, the plungers 13 are moved inwardly by the action of the cam lobes and fuel is expelled from the drilling 12 to said one end of the bore. The flow of fuel to said one end of the bore moves the shuttle piston 19 towards the stop and because of the hydraulic lock in the intermediate portion of the bore, the shuttle piston 20 i also moved towards the stop. The movement of the second shuttle piston causes fuel to be expelled from the end portion of the bore adjacent the stop and this flows by way of the delivery passage 17 to a delivery port 18 and the engine. At a predetermined position of the shuttle piston 20 the spill passage 33 is uncovered and at this time this passage is in register with a spill port 34. The action of opening of the spill passage 33 is to relieve the hydraulic lock which exists between the two shuttle pistons with the result that the shuttle pitson 19 moves into physical contact with the shuttle piston 20 and the two shuttle pistons continue movement until the shuttle piston 20 strikes the stop. At this point the delivery of fuel to the engine ceases. Any excess fuel which remains in the drilling 12 after the shuttle pistons have been halted flows opens the release valve 35 which is located in the first shuttle piston and escapes through the spill passage 33.

Neglecting any leakage of fuel within the apparatus if no fuel is supplied through the filling port 36 then the delivery of fuel to the engine will always occur at a fixed point on the cam lobes. However, by allowing an extra quantity of fuel to flow to said one end of the bore 15 and the drilling to effect a further outward movement of the pumping plungers 13, the commencement of delivery of fuel to the engine will be advanced and with the particular arrangement described the degree of advance is dependent upon the speed.

Having thus described our invention what we claim as new and desire to secure by Letters Patent is:

1. A liquid fuel pumping apparatus for supplying fuel to internal combustion engines and comprising in combination, a pumping plunger, means for imparting inward movement to the pumping plunger in timed relationship with an engine with which the apparatus is associated, a bore to one end of which fuel is supplied under pressure by the pumping plunger during the inward movement thereof, first and second shuttle pistons slidable within said bore, a stop located at the other end of the bore and against which the second shuttle piston is driven during operation of the apparatus, a delivery passage extending from the other end of the bore and through which fuel flows to the engine, means for feeding proportioned quantities of fuel to said other end of the bore and to the portion of the bore lying intermediate the pair of shuttle pistons thereby to effect relative separation of the shuttle pistons and movement thereof away from the other end of the bore until the first shuttle piston is halted, the movement of the shuttle pistons causing outward movement of the pumping plunger, means whereby an additional quantity of fuel may be introduced to said one end of the bore to effect further outward movement of the plunger and valve means operable to permit the escape of any excess fuel from said one end of the bore when the movement of the first shuttle piston is halted.

2. A liquid fuel pumping apparatus as claimed in claim 1 in which the means for supplying an additional quantity of fuel to said one end of the bore includes a control valve the setting of which is responsive to the speed of operation of the apparatus.

3. A liquid fuel pumping apparatus as claimed in claim 2 including a feed pump, a relief valve for controlling the output pressure of the feed pump so that it varies in accordance with the speed at which the apparatus is driven.

4. A liquid fuel pumping apparatus as claimed in claim 3 in which said control valve is exposed to the outlet pressure of the feed pump and is movable thereby against the action of resilient means thereby to control the quantity of fuel which can be admitted to said one end of the bore.

References Cited UNITED STATES PATENTS 3,107,661 10/1963 Kemp. 3,219,020 11/ 1965 Roosa. 3,331,327 7/1967 Roosa 103-5 3,356,031 12/ 1967 Glikin. 3,426,689 2/ 1969 Drori.

DONLEY J. STOCKING, Primary Examiner W. J. KRAUSS, Assistant Examiner US. Cl. X.R. 103-41 

